A Model of Temperature
Inversion Across the White
Mountains, California to Explain
Downslope Migration of Trees
Christopher Van de Ven1, Stuart B. Weiss2,
Connie Millar3, Bob Westfall3,
and Daniel Pritchett4
1 = Albion College, 2 = Creekside Center for Earth Observation
3 = USDA Forest Service, 4 = White Mountain Research Station
Treeline Response to Climate
Change
Peters and Darling, 1985.
Upslope Migration
Millar, Westfall, Delany, 2007
Shift of Aspect
Pinus
longaeva
Granite
Clastic
Limestone
Dolomite
White Mtn. Pk.
1ºC
6ºC
5ºC
4ºC
3ºC
2ºC
Present
1947 at Crooked Creek
2005 at Crooked Creek
1947
2005
Pines in 2005, not in 1947
Downslope Migration
Millar, Westfall, Delany, 2007
•35 iButton temperature data loggers
•Affixed inside 6” lengths of white PVC tubes
•Placed on ground beneath sagebrush
•PVC openings facing north-south
•Recorded hourly temp. Jul. 23-Oct. 6, 2006
Distribution of Sensors
D
at
07
e
/2
Ti
9/
m
20
e
06
08
12
/0
4/
:5
20
1
06
08
14
/1
0/
:5
20
1
06
08
16
/1
6/
:5
20
1
06
08
18
/2
2/
:5
20
1
06
08
20
/2
8/
:5
20
1
06
09
22
/0
4/
:5
20
1
06
09
00
/1
0/
:5
20
1
06
09
02
/1
6/
:5
20
1
06
09
04
/2
2/
:5
20
1
06
09
06
/2
8/
:5
20
1
06
10
08
/0
4/
:5
20
1
06
10
:5
1
All Data for Stations 5 and 8
35
30
25
20
15
10
5
0
-5
-10
-15
Stn5
Stn8
Average Hourly Temperature
All Sites
Crooked Creek All Stations
Average Hourly Temperature July 23- Oct 6 2006
30
25
degC
20
15
10
5
0
-5
0
6
12
Hour
18
24
Hourly Avg. Temp. vs. Aspect
Hourly Average by Aspect
25
20
N
15
degC
S
W
10
E
5
0
0
6
12
Time
18
24
Minimum Temperature Model
• Temperature dependent on
– Elevation
• Higher = colder
– Topographic position
• Valleys get cold air drainage
• Ridges/Peaks are more exposed
Mean Minimum Temperature vs.
Elevation
Mean Minimum Temperature July 23-Oct 6 2006
Crooked Creek
6
5
4
3
degC
2
1
0
-1
-2
-3
-4
3080
3100
3120
3140
3160
Elevation (meters)
3180
3200
3220
Topographic Position
TPI = Elevation – Mean elev. (500m radius)
A. Weiss
Creating the Temperature Model:
Crooked Creek Valley
• Multiple least-squares regression
– Average minimum temp. July 23 – Oct. 6
• Best fit
– Topographic position (500m radius)
– Slope
– Absolute value of topographic position
• R2=0.92
AbsTPI: 0 (blue) to +93 (red)
TPI: -62 (blue) to +99 (red)
Slope: 0º (Blue) to 40º (Red)
Weather Station Data
y = -0.0059x + 20.213
R2 = 0.9898
Avg. Annual Temp (ºC)
Lapse Rate
16
14
12
10
8
6
4
2
0
-2
-4
1000
Bishop; 1252m
Dyer; 1516m
Barcroft
3801m
Crooked Creek
3094m
1500
2000
2500
3000
3500
Elevation (m)
White Mtn. 1 = Crooked Creek
White Mtn. 2 = Barcroft
4000
Cold-Air Drainage
North
South
Cold-Air Drainage with Warmer Air
Temperature
South
North
Thanks!
• Funding from Albion College FDC
grants and Blanchard fellowship, and
from Stanford University
• Stanford-Albion Geobotanical Survey
– Lisa Colville
– Paul Gehres
– Gary Ernst
– White Mountain
Groupies
• White Mtn. Research Station (UC)
• Adelia Barber (UCSC)
• Linah Abaneh (William & Mary) and
Wally Woolfenden (USFS)